The present invention broadly relates to a new and improved construction of an apparatus for measuring the vibrations of gears, especially a spiral bevel gear drive or transmission on a gear testing machine.
In its more particular aspects, the present invention relates to a new and improved construction of an apparatus for measuring the vibrations of a spiral bevel gear drive or transmission on a gear testing machine in which one gear or gear wheel is clamped to or mounted on a headstock to or on an associated spindle. The measuring apparatus possesses a vibration pickup or sensor as well as evaluation devices for evaluating the quality of the gear set.
Measuring apparatuses for measuring mechanical vibrations and impacts also serve for evaluating the quality of gear drives especially the quality of the operating noise. Examples are acceleration pickups as well as vibration pickups, contact microphones, electro-mechanical transducers and piezo-electric transducers. These are fastened to the vibrating object and are connected with an electrical measuring apparatus by means of a flexible cable. The measuring apparatus delivers a frequency analysis with resolution of sonic and vibration signals for example, for comparison with a frame or image mask.
A gear tooth testing machine for testing operating noise in dependence of loading, rotary speed and center spacing is known to the art from Swiss Pat. No. 568,561 or German Pat. No. 2,434,209, respectively. In this machine the spindles are hydrostatically journalled and the pressure alterations in the oil pockets are measured as sonic signals in the liquid. At the radial bearings two oppositely positioned hydraulic oil pockets, usually the vertically arranged pockets on which the applied torsion moment acts, are used as measuring points. Furthermore, according to the disclosure of the above-mentioned Swiss patent, it is known to perform a measurement of the acoustic conduction within a body with the aid of a piezo-electrical converter or transducer for evaluating the quietness of running of gears.
In these known measuring systems the signal receivers or pickups are stationarily installed and only the vertical components of the gear meshing force serves for the measurement. This vertical component, however, is dependent on the geometry of the bevel gear set, for instance, on the spiral or helix angle which can amount up to 55.degree., and in hypoid gear drives, on the displacement of the axes. The result of this is that for helix angles which deviate from 0.degree. and for axes which are displaced from one another vibration measurements carried out in a fixed direction can only evaluate a partial vibration signal.